I have added a sub forum to a forum under my PC, category.Whenever i go to the forum with the sub forum, the sub forum is under all the topic's that is being created in there.How can i make it be at the top?

Example image:So that the theese to forum switches side, which is marked with black arrows.

you can find everything what you are looking for here:Admin panel (advanced) -> general -> Forum -> categories and forums There you can find the green arrows (for up/down) and the yellow icon to edit the forum/category.There you should be able to edit the name.